Method for loading and exploding charges in a borehole



Patented Apr. 24, 1951 METHOD'FGR LOADING AND EXPLODING' 1 CHARGES IN A BOREHOLE JamesR. Hughes, Calipatria,-Calif., assignor, by-

mesne assignments, to

United Geophysical Company, Inc.,. Pasadena, Calif., acorporation of California Application May 14, 1945, Serial No. 593,739

4 Claims, (Cl. 10223) This, invention. is concerned with the loading and exploding of explosive charges-in bore-holes andhas particular application to :seismographic:

prospecting and other operations in which a 1 series of explosive charges-l are exploded in a it ,a

single bore-hole.

In seismog-raphic prospecting -a bore hole is,-v drilled inthe. earth, an explosive charge is loaded thereinto and exploded, and. the resulting seismic waves are picked up-at-the surface oftheeart'n and-:measured with-one orrmore seismographs.

When a series of'charges are to, be explodedinv the samehole, it is frequently: desirableto load more -than one charge into-the-hole at or about the same time and so spaced from each othen in the hole thatithe explosion'of one does not set ofi-the other.

This procedure is economical oil time and :energy, but frequently is impracticable whenthe charges have to be-exploded at or near the same idepthvin the hole; In-such case,- the.

Eli

charges cannot be placed close toreach-other-n initially without danger rof one, setting ,off: .an-

other. .Moreover, in many cases, an-upper-charge cannot-belcwered toward the position of a IOWBXH.

charge after the explosion of'the latter. by reason L of the fact that the explosion frequently caves,

and-.clogs o1 bridges the hole betweenzthe-wrtwo charges. And even when the chargesare to -be: exploded .atpoints sufficiently spaced 7 from each other that. the -..explosion of the lower.- charge cannot setcfi an upper charge,-the upper charge,

may beblown upor completely out-cf the'holea If the charge is merely blown up the hole, the

original-and desired spaced relations-hip of the two charges is altered, and-if the, charge is blown completely youtrof the hole there eisedanger of."

explosion at the surface with consequent'hazard :1

to, persons; and property Asasresult of my investigations I have--dis.-

covered that-whenthe bore-hole is-filledwith fluid; .for example air: (but preferably a liquid;

suchas water or drilling mud) to-a level above the upper. of twovertically spaced charges ;and:: the upper of the two is relatively freetc move down the 'hole, the explosionrof the lower charge.

pointat which the lower charge was exploded .I

have-discovered; moreover, that if theuppfir char e. is permitted to drop in the: hole substanrtially immediately after the Zlowercharge is expl oded ii. 1e. :Within the; few seconds or; so. thereafteriy and :while; the :suctionzcreated the/ext;

plosionlislstillhigh, the .caVing-pithe. holeseldem interfereswith the, lowering of; the upper charge, possibly because the elapsedtime .isuinsufiicientg to permit the hole to become clogged Wlth- SUmciently consolidated fragments from thewallbf the, bore-hole; Whatever bet-theexplanationlthe, l fact remains ,thatunder the, conditions describ'ed-,-, v the upper charge can ,be loweredtoialmostoany desired position in the hole in the-first few sec,-..

ends after the-lowerhcharge isbexplodedlwith' consequent savingin:timerandltrouble involved in cleaning outa bore-hole. betweennshotsewhen a number of charges must be exploded at or about the same depthin the hole,.

Preferably. theeupperl charge .is, held. in vits ini 1tial vertical pcsitionzbyta linehor lines (for .eX-:.-

ample, a shot-fire cable orcables) fastened to the charge and extending up the bore-hole to the; surface. Immediately afterthe lower ,charge;.is'= fired, usually. by an electrically,actuated detonatoror, blasting .capi, ,the lineisupayedout and .the upper chargeispermitted to be, sucked or dragged into the hole to thedesired leveL'further progress. down the hole being prevented hytightening the 1' line-and finally-snubbing it, in the correct/posh tion.

If. desired, a series ofuseveraliupper chargesmay be introduced at the same time, and .jlowered into the holeQone, after the other-gas pr ceding charges are exploded.

It. is desirable, tovernploy a plugin the .hole; above the uppermost charge, to prevent a ,blow-: out of an'unexploded upper chargeysince such; a charge, especially if it contains 'a detonatorl': would create a hazard if it was blown outer the hole and exploded in the open air. Preferably the plug should have in ita vent of, such dimensions or configuration thatcitprevents the charge. from passing upward, and should also be so con' structed that the shot -fire cables 7' connected ;to'- the .charges 7 pass through it freely ,'whenthe. charges are lowered after .each'shot." The plug; should be placed in thech'cle, after the charges arerv initially set and maybe of several forms, as de-' scribed in detail'hereinafter:

I have found that it is desirable to attach tor the upper charge an. expansible member "which?" presses againstthe sidelof the, hole and keeps it' from being blown up thehole when the explosion occurs below it. At the same. time the ex-- Pansiblev membernshouldsbe soeieco ucted that the charge lisgto, be. lowered; .but ,apreferred form.

it-smay be moved .both': up and .dowzrin the :hole during the loading operation;= For example; if

during loading; a charge should be placed too deeplmit may be pulled back up:the. hole to the.

proper level byexerting tension on the shot-fire cable:

De'spite-thefa'ct that with'the device of Fig. 3, the'charge is not anchoredto the sidewall and 2* may-'bemo'ved up:the-bore-hole during-the load- I -10 action-ofthe attachment issuni'cie'ntto hold-the charge :at the correct level during'the explosion:

ing: operationwith relative ease; the xspringin'gof that charge ora lowerone: The reason for this-is not entir'ely apparent, but the fact remains that in many, if not mostinstances', the device of Figt3isat-least as efiic'ient as :thatof *Fig. 2 in preventing a charge from 'being blown'out by the 1 explosionof-a lower-charge. This isparticula'rly true-inh'ard formationsrwhere'the barber-the attachment of Fig. 2 does not-penetrate the wallof thebore-hole to any'subStantiaI de'gree and 1 hence may offer less bearing-surface than is: ob"- tainedwiththe-side of the leafspring in the de'-- vic'e of- Fig." 3.

Referring nowto Fig. 4; it will be seen that it provides-a-means for forming aplug of concrete or other plasticsettabl'e material int'ne bore-hole I The -apparatusfor-forming the plug oomprisesa=circula1 -base=-plate'-'5l or wood or the like, having a center hole 52 through which shotfire cables I 5, l6, 11*(01 other suspending means for the charges) pass. A vertically disposed tube 55 made of cardboard, plastic, metal or the likeizisfiastened to*the baseplate and concentrically around the hole 52 andsis.sofnslightlyir larger diameter-than the-hole. A larger cylindrical member or casing 56 is fastened by means such as-tacks 51, 53 (so that the fastening'may" be -easily brokem- --to the-base plate and extends annular space between the. twortubes above .the...

base. plate.

After the charges have been placed in the borehole, at their initial positions, the sealing apparatus illustrated in Fig. 4 is pushed down the hole by means of a loading pole Si or similar device inserted within the inner tube. As shown in Fig. 5, this loading pole should have a section 62 cut from one side to leave space for the shot fire cables passing through the tube. When the sealing apparatus has been pushed down the hole to a proper level, say slightly above the upper most charge, the loading pole is jerked upwardly and the outer tube or casing 55 is broken loose from the base plate and pulled up out of the hole with the loading pole by means of cords 63, 54 fastened between the loading pole and the upper portion of the casing.

When the outer casing is withdrawn, the concrete (or other loose material) is free to flow outwardly against the wall of the hole and to settle against the screen disk. Preferably the concrete is of such consistency that it is easily handled and at the same time sufficiently fluid to flow tightly against the walls of the hole. Quick-setting cement should be used in the charge.

formationrof thevconcrete .so that the plug will; set -adequa-tely in .a short time, say less-than two .hours.

In'the-practice of that phase of the process: of' my-winvention:which involves the movement I ot su-ccessive charges down the hole :following the explosion of-" preceding charges, the several. charges are-pushed intothe hole to appropriate levels by =means of a conventional loading spoon or a'seriesof conventional loading poles.

tio'n of the severahcharges therein, with a liquid, its-401* example, drilling mud.

It is'edesirable -but 'not essential to provide all charges with an expansible device- (for example that illiistrated imFig.*3) which tends to hold the charges-in position and permits their moven'ent ddwn the hole when pressure or suctionis exerted 'on them; After the charges have been-pIaCedKand spaced-'sufliciently from each other that explesion-of-ca"lowercharge will not set=oiT-'an upper charge'iit is also desirable to fo'rmaplastic plug above the uppermost charge as:described herein'abevep- The use of the plug is primarily a safety measure;

When-L-thecharges and the plug are all in" position, the lowest charge is detonated "'elec' trically. The resulting explosion forces the column of liquid or mud upwardly in the hole,-

in many cases will cause liquid to be squirtedout of the hole at the surface. As the and column of liquid subsides,- a strong suction is created'on the upper charges. usually lasts for several seconds, say 5 or 10.

*"Whilerthis force is effective, the shot-fire cable holding the next lowest charge, say the charge H, is released to permit that charge to be forced down the hole to a desired position, which may be the position originallyoccupied by the lowest W-h'en 'the charge being sucked down thehole has reached the proper depth, it is held" in this-:position by the shot-fire cable and the process is repeated, i. e.,. this charge is fired and have agreat opportunity to bridge or consolidate in the hole while the column of diquid or other fluid is -meving we violently therein and consequently seldomimpede the passage of charges (Town the -hole'.-

As indioatedJit is not-essential to' the aspectof the process just described to use expansible apparatus on the upper charges or to employ the plastic plug. It has been found however, that both of these expedients are desirable not only as safety devices, but also because they appear to aid the carrying out of the process. Apparently the use of an expansible device which holds the charges 01f center in the hole facilitates their being pulled downwardly by the fluid column or by the vibrations set up by the explosion or both.

In the other aspect of the process, involving the explosion of a series of shots at predetermined locations vertically spaced from each other in the bore-hole, the use of the expansible devices on the upper charges is essential to prevent their upward displacement from their original measured positions by explosion of lower charges. But, as already noted, the expansible devices in such case need not be such as to permit downward movement of the upper charges following lower explosions, since no such movement is contemplated. Nevertheless it is convenient The bore hole is sealeidjeither before or after inser-' This suction to use that type of mechan sm, the downward movement being prevented by tension on" the shot-fire cables or the like. Accordingly, this aspect of the invention may be carried out with the apparatus illustrated in Fig. 1 and in the same manner, except that the shot-fire cables are not relaxed to permit the charges to drop when the suction resulting from the explosion of lower charges is imposed. Instead the shotfire cables are kept tense to hold the upper charges in their initial positions.

The use of a plug may be eliminated in very deep bore-holes or whenever it appears that there is no hazard of an unexploded charge being blown to the surface.

As shown in Fig. 1, in a preferred practice of my invention, the charges are held off-center of of the vent in the plug so that, in the event of an accident and consequent movement of" an unexploded charge up the hole, it will'not strike the ventan added safety feature. Quite aside from this feature, however, it is desirable to hold the charge against the side of the hole so as to increase the bearing surface and consequently the resistance to movement of the charge up the hole under the influence of a lower explosion.

I claim:

1. In an operation involving the drilling of bore-hole downwardl in the earth, the loading thereinto of an explosive charge, and the explosion of the charge in the hole, the improvement which comprises loading into the hole a plurality of charges held vertically spaced from each other by a substantial distance, the hole being filled with liquid to a level above the uppermost charge, exploding the lower charge and immediately thereafter releasing and lowering the upper charge in the hole under the influence of a downwardly exerted force created in the lower part of the hole by the explosionof the lower charge the lowering of the upper charge being accomplished before the bore hole is clogged by debris resulting, from the explosion of the lower charge.

2. Process according to claim 1 in which the movement of the upper charge down the hole following the explosion is controlled manually from the surface.

3. In an operation involving the drilling of a bore hole downwardly in the earth, the loading thereinto of an explosive charge and the explo sion of the charge in the hole, the improvement which comprises loading into the hole a plurality of charges held vertically spaced from each other by a substantial distance, disposing a plug in the hole above the uppermost charge, the hole being filled with liquid to a level above the uppermost charge, exploding the lower charge and immediately thereafter releasing and lowering the upper charge in the hole under the influence of a downwardly exerted force created in the lower part of the hole by the explosion of the lower charge, the releasing and lowering being accomplished before the lower part of the hole is clogged by the explosion ofthe lower charge.

4. In an operation involving the drilling of a bore hole in the earth and the explosion of charges therein, the improvement which comprises placing in'the hole two charges spaced longitudinally from each other by a predetermined distance and sufficiently far apart that the explosion of one will not set ofi the other, holding the outermost charge in position in the hole by exerting pressure therefrom against the wallof the hole, the hole being filled with liquid to a point between the outermost charge and the top of the hole,exploding the inner charge, and immediately thereafter releasing the outermost charge and permitting it to be sucked into the hole-before its path is clogged by debris result ing from the explosion of the inner charge. 7

JAMES R. HUGHES. I

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Patented Apr. 24, 1951 ADDITXON OF A DESICCANT TO A FLUIDIZED IRON REDUCTEON PROCESS William L. Slater, In, Alhambra, Calif., assignor to The Texas Company, New York, N. Y., a

corporation of Delaware N Drawing. Application December 24, 1947, Serial No. 793,765

4 Claims.

The present invention relates to catalysts for the synthesis of hydrocarbons, oxygenated hydrocarbons and the like, from carbon oxide and hydrogen, and is more particularly concerned with the step of catalyst reduction.

In accordance with this invention, an oxidized metal of the iron group, such, for example, as ferric oxide or the like, usually associated with suitable promoters, activators, or other modifying agents, is reduced at elevated temperatures and preferably under superatmo-spheric pressure by contact with a stream of hydrogen. Reduction is carried out in the presence of a nongaseous desiccant material effective to take up water promptly as it is produced in the course of reduction and thus enable the reduction to proceed in the absence of or in the presence of a substantially lower partial pressure of water vapor than that which prevails in the absence of the desiccant.

Advantageously, use of the desiccant material is postponed until later stages of reduction, when the reaction between the hydrogen and the remaining oxide becomes excessively slow and difficult. At this time, presence of the desiccant material in the reduction zone appears to speed and facilitate materially the sluggish reaction, substantially increasing the rate of catalyst reduction and resulting in a more completely reduced product. Presumably, this effect follows from the fact that water vapor tends to suppress reduction, while lower water vapor concentrations favor rapid completion of the reaction.

Provision may be made for continuously introducing a solid particle, desiccant material to the reduction zone as a finely divided phase suspended in the flow of hydrogen. As the hydrogen stream circulates cyclically through the reducing zone, the suspended particles absorb water vapor and pass out with the residual hydrogen withdrawn from the zone. Alternatively, a sufficient batch of relatively coarser particle desiccant may be retained in intimate admixture with the catalyst until completion of the reduction step, whereupon pneumatic separation may be efiected by in creasing the flow of reduction gas so that the hydrated desiccant is blown out of the zone. Obviously, in view of the foregoing, any other suitable method of separation may be employed.

The catalyst, reduced as above, is in a form effective for contact with synthesis gas comprising hydrogen and carbon monoxide, under reaction conditions, including an elevated temperature and pressure at which the hydrogen catalytically reduces the carbon monoxide with direct production of desired products, including hydrocarbons and oxygenated hydrocarbons. Preferably, however, such use of the catalyst is preceded by a conditioning treatment, such as is disclosed in copending application Serial No. 570,223, filed December 28, 1944, now U. S. 2,445,795, wherein use is initiated at a temperature substantially below normal operating temperature with a slow increase to operating temperature over a substantial time period.

From the foregoing it will be apparent that an essential characteristic of the present desiccant material or dehydrating agent is that it readily combines with water at the elevated temperature and pressure at which reduction is effected, to form a compound or compounds stable under such conditions. In short, the dissociation pressure of the compound formed by combination of the desiccant with water is lower, at the temperature prevailing in the reduction zone, than the partial pressure of water vapor which would prevail in ordinary operation, preferably less than that partial pressure of water vapor in the gases after condensation at pressures in the order of 100 to 400 pounds per square inch, and at normal temperatures of about 100 F. and preferably about F.

Another desirable feature of the dehydrating agent is that, during the course of hydration, it advantageously tends to disintegrate or crumble into smaller, fluffy particles which can be readily removed from the catalyst by ordinary separating steps or can be swept out by a slight increase in the upfiow of gases. 1

Examples of effective desiccant materials are carbides of aluminum and particularly alkaline earth metals, such, for example, as calcium carbide and barium carbide, which combine chemically with water vapor to form corresponding alkaline metal oxides and liberate gaseous acetylene. The carbides of the rare earth metals are also useful in this respect. On the other hand, metal hydrides, such for example, as calcium or barium hydride, are similarly effective to combine with water vapor, simultaneously liberating additional hydrogen to supplement the stream of reducing agent. It is to be noted that substances such as calcium oxide, barium oxide and magnesium oxide, which chemically combine with water to form the hydroxides and substances such as calcium sulfate and the perchlorates of magnesium and barium which form hydrates, are also useful as desiccants in the present process.

Agents which remove water by chemical combination are, in general, more suitable for use in reduction steps carried out at relatively high tem peratures, as for example, in the range of about 600 to 800 F., as contrasted With those which form hydrates, which are usually effective at lowery' temperatures, for example, below about 400 F. That is to say, compounds that are formed by chemical interaction of the water and desiccant are more stable since they require higher tem peratures to convert them to their anhydrides.

The reduction of the catalyst contemplated, in accordance with the present invention, may be carried out at the lower temperature ranges, but is preferably effected in the case of a catalyst comprising iron, at temperatures ranging above about 600 F., as for example, 650 to 700 F., frequently under more elevated temperatures up to 1000 F. and above, usually under superatmospheric pressure, ranging, for example, up to 200 to 400 pounds per square inch and normally is accompanied by formation of substantial amounts of water.

As the reduction approaches completion, the reaction slows considerably in the presence of only small proportions of water vapor. Accordingly, even where the hydrogen is continuously passed through the reduction zone, withdrawn, dried and recirculated, at substantial rates, completion of the reduction requires excessive time and results in an uneconomical loss of highly diffusible hydrogen. This follows from the fact that dry hydrogen introduced to the zone is promptly contaminated with product water vapor.

Therefore, the present invention efiects a substantial increase in rate of reduction by the removal of water vapor as it is formed so that the partial pressure of water vapor is substantially lowered in the reduction zone. Thus the decrease in the reduction rate normally encountered toward the end of the operation is overcome. This permits reduction at lower temperatures and at lower rates of hydrogen circulation of the reducing gas than hithertofore. Therefore, the preparation of substantial quantities of catalyst may be effected with a more economical utilization of hydrogen and less loss of time, and the final product may be more fully and completely reduced. In particular, the saving in hydrogen lost by diffusion during more extended treatment may involve a substantial economy in operation.

As intimated above, it is contemplated employing the desiccant in solid particle form, preferably in the form of powder or within the same or similar particle size range as the catalyst particles so that intimate contact is effected within the reaction zone.

The catalyst powder is usually in the form of a mass of solid particles disposed loosely within the zone and preferably aerated to a dense fluid phase by means of the upfiowing reducing gas. The invention, however, is not thus limited, and broadly contemplates the reduction of any suitable synthesis catalyst, whether in the form of fluid or stationary bed of fixed particles. In the fixed bed type of operation, or even with so-called moving beds of catalyst, the particles may be in relatively coarse form, providing substantial internal free space through which a finely powdered desiccant will flow when suspended in the reducing gas.

In either case, introduction of desiccant particles as a suspended phase entrained in the reducing gas results in immediate distribution and intermixture of the desiccant with the mass of catalyst particles. Operating in this manner,

separate provision for mixing and distributing the desiccant in the catalyst powder is obviated.

As intimated above, the rate of gaseous fiow through the fluid phase catalyst mass, and degree of subdivision of the desiccant powder may be regulated so that the catalyst particles remain within the reduction zone while the desiccant is withdrawn with the effluent hydrogen. This can be effected with the catalyst in either dense fluid phase, or fixed bed condition. Or, somewhat larger particles of desiccant may be retained in the zone, at least until the particles have completed chemical reaction with the water vapor and assume a more buoyant condition at which they are entrained in and removed in the circulating flow of reducing gas.

Alternatively, a stoichiometric quantity of desiccant may be mechanically mixed with the catalyst and the reduction completed under flow rates at which entrainment of solid particles is negligible, and thereafter, the flow rate increased to a value at which the more buoyant desiccant particles are in effect blown out of the catalyst.

Provision may be made for filtering, electrostatically separating or otherwise removing particles from the effluent hydrogen. Similarly, any conventional means of separation may be employed to recover desiccant solid from the treated catalyst. For example, magnetic separation affords an effective means whereby the final reduced catalyst is preferably rendered substantially free from the added solid desiccant.

In accordance with one method of operation, a stream of hydrogen is continuously passed through a mass of iron oxide powder, comprising mainly F6304 and FezOs finer than about mesh and containing a more or less uniform distribution of particles down to about 20 microns in diameter. Preferably, the hydrogen is passed upwardly through the mass at a temperature of about 700 F. and at a suitable linear velocity such that the catalyst particles are held in a dense fluid phase without material entrainment in the effluent gas. Unconsumed excess hydrogen is withdrawn from the top of the dense fluid phase, cooled to condense contained moisture and separated from the condensed water. Thereafter, it is usually continuously reheated, and continuously recycled to the inlet with an appropriate supplement of fresh hydrogen to maintain the required flow.

Under these conditions, reduction of the catalyst proceeds at a fairly rapid rate until somewhat above about per cent of the oxide has been reduced to metallic iron.

At this point, a batch of powdered calcium carbide is thoroughly mixed with the catalyst in at least the stoichiometrical proportion effective under the temperature and pressure conditions prevailing to absorb the water vapor formed during subsequent reduction. Recirculation of the hydrogen is continued as before, until at least and preferably per cent of the catalyst has been completely reduced, and the desiccant is then separated from the catalyst by any desired means. I

In accordance with one specific embodiment of the present invention, there is provided about 750 pounds of an alkali impregnated ferric oxide finer than 35 mesh, about 80 per cent being finer than 100 mesh, and about 30 per cent being finer than 325 mesh.

The ferric oxide contains approximately 2 per cent alumina and about 1 per cent potassium, 

